The increasing demand for rapidly solidified splat foils from metallic melts is accounted for by the fact that the high solidification rate ensures a very fine structure which is indispensable for optimum properties of the resulting material and for further processing. For example, a solidification rate of more than 10.sup.5 .degree.C./s causes aluminium alloys containing a few weight percent iron to change from a brittle state with low corrosion resistance to a ductile and corrosion-resistant state with a high elevated-temperature strength. The known processes and devices do not, however, permit this alloy to be produced economically, since the proportion of coarser alloy particles which solidify at an inadequate rate is still too large to quarantee good properties of the resulting product.
The known atomizing processes for the rapid solidification of metallic melts produce only a small proportion of high-quality granulate having the optimum structure. Using a rotating perforated siphon, the melt particles are spun from the openings onto cooling plates where they spread into long, thin flakes or foils and rapidly solidify. The throughput achieved with this device is, however, not satisfactory. Furthermore, this method cannot be used in the processing of high temperature and aggressive melts, for instance on refractory metals such as titanium, vanadium, niobium, chromium, or on some superalloys of nickel or cobalt, since these melts react strongly with the material of the device at temperatures of around 1200.degree. C. and higher. The same deficiencies exist in the atomizing processes which disintegrate the melt with a pressurized gas; either the pressurized gas or the materials in contact with the melt strongly react with it.
Additionally, processes are known which work either with (a) stationary or slowly moving cooling surfaces arranged concentrically at a particular angle to the trajectory of the incident melt droplets, or (b) a rapidly rotating cylinder in the axis of which the spray source is located. The latter arrangement leads to a heavy thermal load on narrow annular zones, as well as to the danger that the incident melt droplets adhere and form a thick structure of overlapping, fused particles of solidified melt. In addition, the centrifugal force presses the incident particles onto the interior wall of the rotating cylinder. This causes difficulties in the detachment and removal of the particles. Also, at the rotational speeds required for the production of thin splat foils, the use of cylinders of larger diameters results in an unbalanced state. This defect is intensified by the irregular distribution of the accumulated melt particles.